ngect.engine module

Performance

class ngect.engine.ArrayPerformance(ac_rev: str | None = None)

Bases: object

Compute array performance metrics for ngVLA.

This class loads array configuration and receiver specifications and provides helpers to map requested observing setups to supported receiver bands and to compute sensitivity/observing time metrics.

Attributes

subarraylist[str]: Available subarray names loaded from configuration.
receiverlist[str]: Available receiver band names loaded from receiver data.
_ac_dtdict: Subarray configuration dataset for the selected revision.
_rx_dtdict: Receiver configuration dataset (latest by default).
_co_dtdict: Correlator-related constants used in calculations (e.g., eta_c, eta_Q).

ect(input)

Compute exposure time/sensitivity metrics for a given setup.

Parameters

inputdict: Input parameters containing at least the following keys: - freq (astropy.units.Quantity): requested observing frequency. - theta (astropy.units.Quantity): target angular resolution. - subarray (str): subarray name. - specmode (str): “cont” or “line”. - chanwidth (astropy.units.Quantity): channel width (velocity or frequency). - npol (int): number of polarizations. - tos (astropy.units.Quantity): on-source integration time. - elevation (astropy.units.Quantity): elevation angle. - ectmode (str): calculator mode (e.g., “tos2rms”). - pwv (str): precipitable water vapor setting.

Returns

dict: Mapping with computed quantities such as: freq, rx_name, fov, max_bw, t_sys, chanwidth_freq, chanwidth_velo, tos, sigma_fl, sigma_tb, num_ant, theta, eta_A, total_eff_A, and auxiliary efficiency factors.

Raises

ValueError: If the requested frequency is unsupported by any receiver band.

Notes

This method performs both instrument configuration lookups and several numerical interpolations (e.g., cubic splines) over band-dependent system temperature and aperture efficiency curves. The implementation is adapted from the reference ngVLA sensitivity calculator.

freq_to_receiver(freq)

Return receiver bands that support a requested frequency.

Parameters

freqastropy.units.Quantity: Requested sky frequency (e.g., 10 * u.GHz). May also be a plain float interpreted as GHz, but a Quantity is recommended.

Returns

list[str]: List of receiver band names whose frequency coverage includes the requested value. Multiple bands may include a given frequency where they touch/overlap.

Raises

ValueError: If the requested frequency is outside the range supported by all receivers.

get_receiver(rx): Get receiver properties.

Notes

This method is a placeholder and may be implemented in a future revision to return a structured view of receiver parameters.

nearest_supported_frequency(freq: Quantity) → dict

Find the nearest supported receiver band edge to a requested frequency.

Parameters

freqastropy.units.Quantity: Requested sky frequency. Must be a quantity with frequency units (e.g., 10 * u.GHz).

Returns

dict

A mapping with the following keys:

unit: always "GHz".
band: receiver band name (e.g., "BAND_1").
freq: nearest band-edge frequency as a float in GHz.
range: a mapping with keys low and high giving the band limits in GHz.

Notes

The search considers both low and high edges of every band and returns the one closest to the requested frequency.

Examples

>>> from ngect.engine import ArrayPerformance
>>> from astropy import units as u
>>> ap = ArrayPerformance()
>>> ap.nearest_supported_frequency(0.5 * u.GHz)["freq"]
1.2